Fast positionable X-ray filter

Abstract

The preferred embodiment of the disclosed invention comprises rotary actuators that move one or more x-ray attenuating plates in the x-y plane (ie. image plane). These x-ray attenuating plates attenuate the x-ray beam with thin metal sheets or plates that contain one or more apertures, which fully exposes the desired region of interest (ROI) while filtering the rest of the image, reducing the radiation exposure for the procedure. The devices will typically have a selection of many attenuation profiles. A small aperture or low attenuation profile region will result in a higher total exposure reduction and a large aperture or large attenuation profile will result in a smaller exposure reduction. The x-ray attenuating plate can be rotated to select an attenuation profile using a detent wheel.

The invention claimed is: 
     
       1. An X-ray dose reduction device comprising:
 a plurality of rotary electromagnetic actuators; and 
 a set of fixed attenuation profiles; 
 wherein said plurality of rotary electromagnetic actuators select and position one or more of said set of fixed attenuation profiles anywhere in an image area. 
 
     
     
       2. A method for reducing a radiation level used when an X-ray image is created, said method comprising the steps of:
 selecting an area-of-interest in said X-ray image; 
 exposing said area-of-interest using a fixed attenuation profile; 
 wherein exposing said area-of-interest using a fixed attenuation profile comprises selecting said fixed attenuation profile from a set of fixed attenuation profiles using one or more rotary electromagnetic actuators; 
 positioning said fixed attenuation profile such that a lowest attenuating region overlaps said area-of-interest using the one or more rotary electromagnetic actuators. 
 
     
     
       3. The method for reducing a radiation level used when an X-ray image is created as in  claim 2 , wherein selecting the fixed attenuation profile from a set of fixed attenuation profiles using one or more rotary electromagnetic actuators and positioning the fixed attenuation profile comprise selecting and positioning said fixed attenuation profile with the one or more rotary electromagnetic actuators. 
     
     
       4. The method for reducing a radiation level used when an X-ray image is created as in  claim 2 , wherein said fixed attenuation profile comprises at least one region that does not attenuate an X-ray beam. 
     
     
       5. The method for reducing a radiation level used when an X-ray image is created as in  claim 2 , wherein said fixed attenuation profile comprises a higher attenuating region and a lower attenuating region, and said lower attenuating region is at least as large as the area-of-interest. 
     
     
       6. The method for reducing a radiation level used when an X-ray image is created as in  claim 2 , wherein the area-of-interest is exposed using the fixed attenuation from a set of fixed attenuation profiles at a first refresh rate and said fixed attenuation profile from a set of fixed attenuation profiles is removed from the full image area at a second refresh rate slower than said first refresh rate.